In collecting refuse, the refuse is generally picked up at individual locations, such as homes, and loaded into a storage body mounted on a truck. When the storage body becomes full, the truck must make a trip to a dumping point to unload the refuse. Depending upon the location of the dumping point, the time required for dumping can be quite substantial. This time is lost time since the refuse collection apparatus performs merely as a truck during its trip to and from the dumping site.
To reduce lost time spent in transporting refuse to the dumping site, modern refuse collection equipment functions by packing the refuse under high pressures within a storage body. The capacity of the refuse collection apparatus is, thereby, increased, and it is able to function by collecting refuse for a longer period of time before having to make a trip to the dump.
In refuse collection equipment presently in use, the storage body is mounted on a truck frame and mounted behind the storage body is a tailgate structure. The tailgate includes a loading hopper and packing means for removing the refuse from the hopper and packing it under high pressure within the storage body. It is common practice to mount a movable ejection panel within the storage body. During the packing operation, refuse is packed against the ejection panel which moves forwardly within the storage body as the packing operation progresses. When the storage body is completely full, the ejection panel has moved all the way forward to a position adjacent the front of the storage body. During the dumping operation, the tailgate structure is pivoted upwardly with respect to the storage body and the refuse is ejected by moving the ejection panel rearwardly to push the refuse out of the storage body.
Present refuse collection apparatus is rather large and unwieldly as a result of several factors. First, the tailgate structure which contains the packing mechanism is relatively long, and extends outward a considerable distance from the back of the storage body. The length of the tailgate structure is dictated, to a large extent, by the shape of the loading hopper defined in the lower portion of the tailgate. Present loading hoppers have a generally uniformly curved bottom which slopes gradually downward from a loading lip at the rear of the hopper to a low point and then gradually upward to an inclined passage which leads into the storage body. A panel is rotated through the hopper with the lower edge of the panel following along the curvature of the hopper bottom. Due to the curved configuration of the hopper bottom to accommodate rotation of the panel, the hopper is relatively long and shallow. Thus, the tailgate structure must also be relatively long which produces a tailgate whose center of mass is positioned a considerable distance rearward of the tailgate supporting structure.
A further factor contributing to large and unwieldly refuse collection equipment is the movement of the packing means within the tailgate structure. Many refuse collectors which use pivotally interconnected upper and lower panels for packing (see U.S. Pat. No. 3,143,230), employ an upper panel which is reciprocated in a straight-line movement between an upper and forward position and a lower and rearward position. To provide a high horizontal force component to the upper panel, the straight-line path must have a slope which provides substantial horizontal movement to the panel. This, in turn, requires that the tailgate structure be relatively long.
In present refuse collection equipment, the storage body is made from relatively heavy structural members to accommodate the high internal pressures imposed on the body. The high weight of the structural members further contributes to making the refuse collection equipment unwieldly. Added weight in the refuse storage body requires additional weight in the structural members for the truck frame which also increases the weight of the vehicle. As the length and weight of the vehicle are increased, it becomes increasingly more difficult to maneuver in congested areas in picking up refuse.
As stated, modern refuse collection equipment functions by packing refuse under high pressures within a storage body mounted on the frame of a truck. In present equipment, little or no packing is accomplished within the loading hopper. The refuse is merely swept from the hopper by rotation of a panel and packing does not occur until the refuse is moved into the storage body. To accomplish more uniform packing, it would be desirable if some of the packing could take place within the loading hopper.
During the packing operation, the refuse is moved into a storage body and compacted against an ejection panel. As the refuse is compacted, it may be moved in an upward direction against the top of the refuse storage body and impose large stresses on the top of the body. To accommodate these stresses, the top of the refuse body will have to be heavily reinforced and, therefore, heavy.
As the packing continues, the ejection panel moves forwardly within the storage body. The movement of the ejection panel is generally controlled by a telescopic hydraulic cylinder in which the effective hydraulic area within the cylinder varies with its degree of extension. As the ejection panel moves forwardly, the refuse within the body also moves as new refuse is packed into the body. The friction between the refuse within the body and the side walls of the body varies depending on the amount of refuse in the body. Due to the various factors which affect movement of the ejection panel and refuse within the body, it is difficult to obtain uniform compaction of the refuse throughout the storage body. Refuse in one region of the storage body may be very densely compacted while refuse in another region may be less densely compacted. It would be desirable to obtain compaction throughout the body at relatively high and uniform compaction pressures at or near the maximum pressures generated by the packing means since this would permit packing more refuse into a storage body of a given volume.